This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for STAAR Visian Toric ICL Post-Approval Study (NCT04516772), a na na study. The primary outcome is Change in Axis Orientation of the TICL.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04516772 |
| Phase | NA |
| Condition | Myopic Astigmatism |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 125 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Staar Surgical Company |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns people with myopic astigmatism who received the Visian Toric implantable collamer lens. The primary outcome population is narrower: it counts primary, or first implanted, eyes with qualifying lens rotation between 18 and 24 months after surgery.
Intervention
The intervention is the Visian TICL, a toric implantable collamer lens described as intended for the correction or reduction of myopia with astigmatism. This is a device study, not a comparison of drug regimens.
Comparator
No separate comparator group is described. The study is recorded as single-group, with allocation listed as NA. The stated outcomes therefore do not support a like-for-like comparison against another treatment or a control arm.
Primary question
The primary question is how many primary implanted eyes had TICL rotation of less than or equal to 5 degrees between 18 and 24 months postoperative. The registry description states a performance criterion of rotation within that limit in 90% of treated eyes. The observed count, denominator, and whether the criterion was met are not reported in the registry record.
The study objective is to evaluate long-term clinical performance, with the brief summary specifying a 24-month horizon. The primary outcome focuses on rotational stability over a defined late postoperative interval. That focus is distinct from visual outcomes or the overall correction of refractive error; those outcomes are not described by the primary endpoint definition. A statistical reading must therefore keep the question narrow: it concerns the frequency of eyes meeting a rotation threshold in a specified interval, not a causal comparison or a complete assessment of every aspect of lens performance.
3. Trial Design
The registry record identifies NCT04516772 as the STAAR Visian Toric ICL Post-Approval Study. It lists the study as completed, with enrollment of 125, a start date of 2020-07-21, and primary completion on 2024-12-11. The phase is listed as NA. The sponsor is Staar Surgical Company.
The design is recorded as single-group, and allocation is NA. Masking is listed as NONE. The intervention is the Visian TICL device, described as intended for correction or reduction of myopia with astigmatism. No concurrent control arm or randomized assignment is described. The record therefore supports a descriptive account of outcomes among treated participants, but not a treatment-versus-control effect estimate from this study.
The brief summary identifies evaluation of long-term performance over 24 months. The primary endpoint specifies a later interval, from 18 to 24 months postoperative, and counts primary implanted eyes with lens rotation at or below the stated threshold. Several secondary outcomes concern absolute rotation across adjacent visits, from the operative visit through Month 24. These outcomes address rotation over multiple periods, but their results are not reported in the registry record.
The distinction between participants and eyes matters. Enrollment is recorded as 125, while the adverse-event information uses an all-eyes group with 232 eyes at risk. The primary endpoint refers specifically to primary eyes, but its analysis denominator is not reported in the registry record. The record does not explain the relationship between participant enrollment, treated eyes, and the population analyzed for the primary outcome. The status and design descriptions should therefore be read as registry metadata, not as a substitute for the missing outcome-level analysis details.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Visian TICL |
|---|---|
| STARTED | 125 |
| COMPLETED | 111 |
| NOT COMPLETED | 14 |
Reasons for not completing this period:
| Reason | Visian TICL |
|---|---|
| Withdrawal by Subject | 3 |
| Lost to Follow-up | 7 |
| Adverse Event | 4 |
Analysis population for the primary outcome, as defined in the registry: The number of primary (first implanted) eyes with TICL rotation less than or equal to 5 degrees between 18 and 24 months postoperative.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
Population: Baseline data were collected on the whole participant level
| Characteristic | Unit | Visian TICL |
|---|---|---|
| Participants analysed | 125 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 125 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 77 |
| Sex: Female, Male: Male | Participants | 48 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 1 |
| Race (NIH/OMB): Asian | Participants | 32 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 10 |
| Race (NIH/OMB): White | Participants | 81 |
| Race (NIH/OMB): More than one race | Participants | 1 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 125 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Axis Orientation of the TICL, measured over 18 to 24 months postoperative.
| Element | Registry entry |
|---|---|
| Result type | Count Of Units |
| Measure of spread | not applicable |
| Unit | Eyes |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is titled Change in Axis Orientation of the TICL. Its unit is eyes, and its timeframe is 18 to 24 months postoperative. The outcome counts primary, first implanted eyes whose TICL rotation was less than or equal to 5 degrees during that interval. The registry description states a target condition of rotation within this limit in 90% of treated eyes.
This is a threshold-based count outcome. It classifies eyes according to whether their measured rotation falls within the specified limit, rather than reporting a continuous average rotation value. Such an endpoint can make a clinically defined performance criterion easier to interpret: the reader can ask how many eyes met the stated stability threshold. However, the binary count does not show how far measurements were from the threshold, nor does it describe the distribution of rotation among eyes that met or did not meet it.
For interpretation, the count must be read with its denominator and the observation rules. The registry record does not report the observed count, denominator, confidence interval, or endpoint analysis. It also does not report how an eye with missing follow-up measurement was handled. Without those details, the stated criterion describes what the endpoint is intended to assess, not the observed level of performance or the precision of an estimate.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive limitation is that the registry record defines the primary endpoint but does not report its observed result. It specifies a count of primary implanted eyes with TICL rotation of less than or equal to 5 degrees between 18 and 24 months postoperative, and describes a criterion involving 90% of treated eyes. It does not give the count, the denominator, an estimated proportion, or an uncertainty interval. Consequently, the posted record does not establish whether the criterion was met or how precisely the endpoint was estimated.
The study is single-group, with allocation listed as NA and masking listed as NONE. Accordingly, the design is suited to describing what was observed among participants receiving the device, but it does not provide a randomized comparison against an alternative. Even if the primary endpoint result were available, an outcome frequency in this design would not by itself establish what would have happened to comparable participants under another intervention or without the device. The registry record does not describe a control group for this question.
The outcome concerns a specific aspect of device performance: rotation over a late postoperative interval. It is not a comprehensive measure of refractive correction, visual function, or all possible benefits and harms. The secondary outcomes listed in the record also concern absolute rotation across visit intervals. Their inclusion signals a broader assessment of rotation over time, but no results for those measures are reported in the registry record.
The safety information records 29 serious adverse events among 232 eyes in the All Eyes group and 2 non-ocular serious adverse events among 125 people at risk in the Non-Ocular Serious Adverse Events group. It also records 40 other adverse events in the All Eyes group and zero deaths in each listed group. These counts should be interpreted with their stated populations and denominators; they are not comparative risk estimates. The registry record does not establish event attribution or provide a control-group contrast.
The evidence available supports a careful description of the intended endpoint, study structure, and posted adverse-event counts. It does not support a conclusion about whether the endpoint target was achieved, the size of a treatment effect, or the balance of benefits and harms. Precision cannot be judged without the missing endpoint estimate and its uncertainty. Statistical significance is also not assessable from the posted primary outcome information because no inferential result is reported.
9. Statistical Methods Explained
The primary outcome is a count of eyes satisfying a threshold. For each primary implanted eye, the endpoint asks whether lens rotation was less than or equal to 5 degrees in the interval from 18 to 24 months postoperative. The resulting count is meaningful only alongside the number of eligible eyes assessed. A count without its denominator cannot establish the proportion meeting the criterion, and the registry record does not report either the observed count or the primary analysis denominator.
What does a threshold-based endpoint show?
In general, a threshold endpoint turns a measurement into a category: an eye either meets the stated limit or does not. This can make a prespecified performance criterion straightforward to communicate. The trade-off is that categorization discards detail. Eyes just within the limit and eyes with much smaller rotation receive the same classification, while eyes just outside the limit and eyes with substantially greater rotation are grouped together. A continuous summary or a distribution of measurements can answer different questions, but the registry record does not report such results for the primary endpoint.
Why would uncertainty matter?
In general, an estimate from a finite set of observations is subject to sampling variability. A confidence interval expresses a range of values compatible with the observed data under a stated statistical method and its assumptions. A narrow interval indicates greater precision than a wide interval, though precision is not the same as freedom from bias. No confidence interval for the primary outcome is reported in the registry record. Without the estimate and interval, the reader cannot judge the precision of the proportion of eyes meeting the criterion.
What does the single-group structure imply?
A single-group study describes outcomes among people receiving the intervention. It does not create the balance of measured and unmeasured factors that random allocation is designed to support across comparison arms. In general, a before-and-after or follow-up result may describe change or status over time, but attributing that outcome to the device requires a suitable comparison and assumptions beyond the observed group alone. Here, the registry record lists no separate comparator group, and it does not report a comparative primary analysis. The endpoint should therefore be read as a measure of observed rotational performance, not a randomized treatment effect.
How should repeated visits be understood?
The listed secondary outcomes measure absolute rotation between successive visits, beginning with the operative visit and continuing through Month 24. These are distinct intervals, not interchangeable measures. In general, repeated observations from the same eye may be statistically related; treating them as independent observations without accounting for that relationship can misstate uncertainty. The registry record does not report the statistical methods used for the secondary outcomes, whether repeated measurements were modeled jointly, or how changes between visits were summarized. It also does not report analyses for those outcomes.
What role could over-dispersion have?
For count outcomes, a simple model may assume that variation follows a specified distribution. In general, over-dispersion means the observed variation is greater than that model expects. If present and ignored, standard errors and uncertainty intervals can be too small, making results appear more precise than they are. The primary endpoint is a count of eyes meeting a criterion, not a count of recurrent events per eye, and the registry record reports no dispersion estimate or model. It would therefore be inappropriate to assert that over-dispersion occurred or that a particular count model was used.
What can be said about planning calculations?
Any sample-size figures associated with a planning illustration should not be mistaken for the study's enrollment plan or for observed power. The described illustration uses a two-sided significance level of 0.05, equal allocation between two hypothetical arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. Those assumptions do not describe the recorded single-group trial design. A planning calculation is a hypothetical design aid, not evidence that the study had a particular probability of detecting its result after completion. The registry record does not report the trial's own sample-size justification or design assumptions.
Overall, the registry record does not report the primary endpoint's statistical analysis method, any inferential result, or the assumptions needed to reproduce an estimate. The endpoint definition is interpretable, but a complete statistical assessment requires the observed data summary, denominator, uncertainty, and analysis details.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists 39 outcome measures and identifies several secondary outcomes for absolute TICL rotation between successive visits, spanning the operative visit through Month 24. Looking at multiple outcomes or intervals creates a general multiplicity concern: the more statistical questions examined, the greater the chance that some result may appear unusual by chance if each is judged separately. In general, prespecifying a primary question and an approach to multiplicity helps readers distinguish confirmatory inference from exploratory analyses. The registry record does not report a multiplicity-adjustment strategy, a hierarchy for secondary outcomes, or endpoint-specific analysis results.
Missing-data handling is also not reported in the registry record. The primary endpoint requires follow-up information for the 18-to-24-month interval, but the record does not state how eyes without an available measurement were treated, whether any observations were excluded, or whether imputation was used. These choices can affect both the denominator and the interpretation of a threshold-based count. The number of eyes included in the primary endpoint analysis is not reported.
The primary population is described as primary, or first implanted, eyes. The record does not explain the analysis population beyond that definition, nor does it report whether all eligible eyes were analyzed according to a prespecified rule. It also does not report sensitivity analyses for missing observations or alternative analysis populations. These absences prevent assessment of how robust an endpoint estimate might be to incomplete follow-up or analysis choices. They should be treated as unreported methods, not as evidence that a particular method was or was not used.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| All Eyes | 29 | 232 | 12.5% |
| Non-Ocular Serious Adverse Events | 2 | 125 | 1.6% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| All Eyes | 0 of 232 |
| Non-Ocular Serious Adverse Events | 0 of 125 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| All Eyes | 40 of 232 |
| Non-Ocular Serious Adverse Events | 0 of 0 |
Most frequent serious adverse event terms
| Event term | Organ system | All Eyes | Non-Ocular Serious Adverse Events |
|---|---|---|---|
| Residual refractive error | Eye disorders | 10 of 232 | 0 of 125 |
| Intraocular pressure increased | Eye disorders | 9 of 232 | 0 of 125 |
| Narrow anterior chamber angle | Eye disorders | 6 of 232 | 0 of 125 |
| Pupillary block | Eye disorders | 5 of 232 | 0 of 125 |
| Residual cylindrical refractive error (due to TMICL misalignment) | Eye disorders | 4 of 232 | 0 of 125 |
| Eye pain | Eye disorders | 1 of 232 | 0 of 125 |
| Increase in cylindrical refractive error (due to TMICL rotation) | Eye disorders | 1 of 232 | 0 of 125 |
| Posterior subcapsular cataract | Eye disorders | 1 of 232 | 0 of 125 |
| Intraocular lens dislocation | Eye disorders | 1 of 232 | 0 of 125 |
| Gastric ulcers | Gastrointestinal disorders | 0 of 232 | 1 of 125 |
Most frequent non-serious adverse event terms
| Event term | Organ system | All Eyes | Non-Ocular Serious Adverse Events |
|---|---|---|---|
| Intraocular pressure increased | Eye disorders | 40 of 232 | 0 of 0 |
Serious events with the highest arm-level rate: residual refractive error (4.3%), intraocular pressure increased (3.9%), narrow anterior chamber angle (2.6%), pupillary block (2.2%), residual cylindrical refractive error (due to tmicl misalignment) (1.7%).
The registry record lists safety information for an All Eyes group and a Non-Ocular Serious Adverse Events group. For All Eyes, 29 serious adverse events are recorded among 232 eyes at risk, and 40 other adverse events are recorded among 232 eyes at risk. The Non-Ocular Serious Adverse Events group records 2 events among 125 people at risk. Deaths are recorded as zero in both groups.
These are counts tied to different stated populations and denominators. They should not be combined into a single rate or compared as though the groups were equivalent. The All Eyes denominator is expressed in eyes, while the non-ocular serious-event denominator is expressed in people at risk. The record does not explain whether individuals could contribute more than one event, whether events overlap across categories, or how follow-up time was handled. The counts therefore do not by themselves convey a time-adjusted rate or a causal relationship to the device.
The listed serious adverse event terms and percentages include residual refractive error at 4.3%, increased intraocular pressure at 3.9%, narrow anterior chamber angle at 2.6%, pupillary block at 2.2%, residual cylindrical refractive error due to TMICL misalignment at 1.7%, and gastric ulcers at 0.8%. The registry record does not establish from these entries whether each event was judged related to the device. These figures describe posted safety entries, not a comparison with another treatment or a complete account of clinical risk.
12. What the Result Does, and Does Not, Mean
The study addresses a defined performance question: how many primary implanted eyes had TICL rotation within the stated limit during the 18-to-24-month postoperative interval. That focus is useful for interpreting rotational stability over a late follow-up period. The record also identifies a 24-month study objective and lists several rotation outcomes across successive visit intervals. These details clarify the intended scope of the assessment.
What the posted record does not provide is the observed primary endpoint result. The description that the endpoint concerns rotation within the limit in 90% of treated eyes is a criterion, not evidence that this level was achieved. The record does not state an observed count or proportion, the denominator analyzed, or a confidence interval. It therefore cannot establish whether the criterion was met or how precise an estimate would be.
The design also sets limits on what could be inferred. Because the study is single-group and does not describe a comparator, it cannot provide a like-for-like estimate of outcomes under an alternative intervention. The posted information describes a device cohort and adverse-event counts, but it does not establish that observed outcomes were caused by the device or how they compare with outcomes under another approach.
The endpoint is not a complete measure of visual or refractive outcomes, and safety counts are not a substitute for comparative safety analysis. The registry record does not report the endpoint's inferential analysis, missing-data methods, or multiplicity plan. These omissions leave uncertainty about analysis populations, precision, and the interpretation of multiple outcomes.
Accordingly, the registry record supports a description of the study's purpose, design, endpoint definition, and listed safety events. It does not support a conclusion that the lens did or did not meet its stated performance criterion, a quantified treatment effect, or a definitive comparative safety conclusion. The distinction is between what the endpoint was designed to assess and what the posted results actually document.
13. Why This Trial Matters Statistically
This study illustrates why endpoint definitions and observed results must be kept separate. The primary endpoint sets a clear threshold for rotational stability and identifies the follow-up interval in which it is assessed. Yet a threshold and a target criterion do not reveal the observed outcome. The missing count, denominator, and uncertainty estimate prevent readers from judging either the endpoint's result or its precision.
It also highlights the importance of matching interpretation to design. A single-group post-approval study can describe outcomes among treated participants and record events over follow-up. It cannot, without a suitable comparator, answer the same causal question as a randomized comparison. This distinction is especially important when a result is expressed as a percentage or count: descriptive performance in a cohort is not automatically a comparative treatment effect.
The record presents another common challenge in device studies: the unit of analysis may vary. Enrollment is stated in participants, the primary endpoint counts eyes, and safety information includes an all-eyes denominator as well as a people-at-risk denominator for non-ocular serious events. Clear reporting of the analyzed population and the relationship between people and eyes is needed to interpret each statistic correctly.
Finally, the many listed outcomes make transparent statistical methods important. Reporting how multiplicity, incomplete follow-up, repeated observations, and analysis populations were handled helps readers assess the credibility and precision of results. Those methods are not reported in the registry record. The study is therefore useful as an example of why a clearly described objective is only one part of statistical interpretation: complete outcome reporting and design-aware inference are also necessary.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The primary limitation for interpreting this study is the absence of its observed primary endpoint result in the registry record. The count of eyes meeting the rotation criterion, the denominator, and an estimate of uncertainty are not reported. Without these, the endpoint's result and precision cannot be assessed.
The primary population is described as first implanted eyes, but the record does not report the number of such eyes analyzed or explain their relationship to the enrollment of 125. The safety record uses 232 eyes in its All Eyes group. The record does not explain the correspondence between the participant and eye populations, so those denominators should not be treated as interchangeable.
The study is single-group, with no separate comparator described. As a result, the record does not offer a like-for-like control comparison. Masking is listed as NONE, but the record does not describe the measurement procedures or safeguards used to reduce assessment bias for axis orientation. These details are not reported in the registry record.
The registry record does not report missing-data methods, the statistical analysis plan, multiplicity handling, or analyses for the listed secondary outcomes. It also does not provide enough information to assess whether repeated measurements were modeled with their within-eye relationship taken into account. The absence of these details limits evaluation of robustness and reproducibility; it does not establish that the methods were inadequate.
Finally, the posted serious adverse event counts do not identify comparative risks or, from the information recorded, establish event attribution. They are useful descriptive entries, but they cannot alone support a complete safety assessment.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: STAAR Visian Toric ICL Post-Approval Study — NCT04516772.
- Registry record last updated 2026-03-13; status last verified 2026-03.
- Results first posted 2026-03-13.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT04516772 is the completed STAAR Visian Toric ICL Post-Approval Study, sponsored by Staar Surgical Company. The registry record lists a single-group device study with enrollment of 125, no masking, phase NA, and a start date of 2020-07-21. Primary completion is recorded as 2024-12-11.
The primary endpoint counts primary implanted eyes with TICL rotation of less than or equal to 5 degrees between 18 and 24 months postoperative. The record describes a criterion involving 90% of treated eyes but does not report the observed endpoint result, denominator, or uncertainty estimate. Secondary outcomes address rotation between successive visits through Month 24.
Safety entries include serious and other adverse-event counts, listed event terms and percentages, and zero deaths in each reported group. The registry record does not report a comparator, primary endpoint analysis, missing-data methods, or a multiplicity strategy. Interpretation is therefore limited to the study structure, endpoint definition, and descriptive safety information recorded.